1. Field of the Invention
The present invention relates to a video playback apparatus and a video display apparatus which reproduce and display an original video in a trick playback mode, such as a fast forward playback mode and a slow playback mode, and also relates to a method for controlling these apparatuses.
2. Description of the Related Art
A television (TV) set which can display video at a high frame rate has recently been commercialized for improving a response of moving images. The TV set converts video signals of 60 frames per second (fps) input from a playback device such as a digital versatile disc (DVD) player into video signals of 120 fps by a built-in frame interpolator and displays the video signals on a screen.
When the video signals recorded in a DVD is reproduced in a trick playback mode, the DVD player adjusts the frame rate by decimating frames in a fast forward playback mode and by doubling the frames in a slow playback mode. The video signals thus, can be output in a fixed frame rate, regardless of a normal playback mode or the trick playback mode, and it enables any type of display device to reproduce and display the video signals.
Japanese Patent Application Laid-Open No. 2001-054066 discusses a video display system which changes decoding processing speed in the fast forward playback mode and the slow playback mode, and rewrites a video random access memory (VRAM) at a different frame rate.
Japanese Patent Application Publication No. 2007-528012 discusses a display method which switches a display scan mode in response to the trick playback mode.
According to a conventional trick playback method, however, the display image reproduced in the trick playback mode does not always have a high image quality in a case where the video from a playback device that can perform a high frame rate playback is displayed by a display device that can display the video at the high frame rate.
FIG. 11 illustrates device setting and a transition of the frame rate in a conventional 2× speed fast forward playback mode. A DVD playback unit 3 reproduces an original video data of 60 fps which is recorded in a DVD by 2× speed fast forward playback, and the original data is converted to playback video data of 120 fps. Since an output video frame rate from a transmission unit 6 is normally fixed at 60 fps, the output video frame rate is decimated and output by a frame doubling/decimating units. Input video data of 60 fps received by a receiving unit 32 in a TV set 31 is converted to the video data with the frame rate of 120 fps by a frame interpolator 34, and displayed.
FIG. 12 schematically illustrates frame images to be displayed. Since the frame images are interpolated after odd-numbered frames of the original video data are decimated, reproducibility of the displayed video is poor.
FIG. 13 illustrates the device setting and a transition of the frame rate at a conventional ¼× speed slow playback mode. A DVD playback unit 3 reproduces the original video data of 60 fps which is recorded in a DVD by ¼× speed slow playback, and the original data is converted to the playback video data of 15 fps. Since the video frame rate from a transmission unit 6 is normally fixed at 60 fps, a frame interpolator 4 and a frame doubling/decimating unit 5 are turned on and the interpolated and doubled video data is output. The video data of 60 fps received by a receiving unit 32 of a TV set 31 is converted to the video data with the frame rate of 120 fps by a frame interpolator 34 and displayed.
FIG. 14 schematically illustrates the frame images to be displayed. An interpolated frame image processed by the frame interpolator 4, a doubled frame image processed by the frame doubling/decimating unit 5, and an interpolated frame image processed by the frame interpolator 34 are inserted between frame images of the original video data. As a result, smoothness of the video to be displayed is lost because three similar frame images continue.